Integration of Soil Bioengineering Into An Erosion and Flood Protection Design On The Urbanized Sacramento River In The City of Sacramento

Traditional engineering approaches to assess horizontal and vertical extents of an erosion and flood protection project would normally require continuous bank protection up to the water surface elevation of the design flow. Such elevation of hard protection, mostly not inundated year-round, creates permanent environmental impacts. Besides, such design does not provide aesthetic values, especially in urbanized areas such as in the Sacramento City.

With an effort to restore and sustain river environments within a bank erosion and flood protection design on the Sacramento River, a robust analysis methodology was developed to transform a design with 100% hard protection exposed almost year-round to a design not only with a minimum invisible footprint of hard protection but also with the creation of a valuable riverine environment. The long-term ecological uplift of the design benefits the riparian habitat for the endangered yellow billed cuckoo, the spawning and nursery habitat and shaded riverine areas for salmonids and green sturgeon, and protection and food sources for these endangered aquatic species throughout their life cycles.

This paper presents a rigorous process of deterministic, qualitative, and statistical analyses to justify the reduction of the height of the hard protection and replace it with soil bioengineering (geogrid planting in encapsulated soil lifts) for ecological uplift and reduction in environmental impacts. It is expected that the softening of the design still effectively provides protection against fluvial and boat wake erosion without compromising the life safety aspect of the flood protection project.